Transmission for motor vehicles



Dec. 28, 1943. K. MAYBACH TRANSMISSIONS FOR MOTOR VEHICLES Filed Dec'.4, 194C? KARL MAYBAC H Patented Dec. 28, 1943 TRAN SlVIISSION FOR MOTORVEHICLES Karl Maybach, Friedrichshafen-on-the-Bodensee, Germany; vestedin the Alien Property Custodian Application December 4, 1940, Serial No.368,540 In Germany December 5, 1939 2 Claims (Cl. 105-962) My inventionrelates to transmissions for motor vehicles and has special reference totransmissions including a hydraulic torque converter or a plurality ofsuch converters. It is of special importance in heavy vehicles driven byinternal combustion engines.

In transmissions of this kind it is desired to develop a high secondaryturning moment for driving the vehicle wheels with the motor revolvingat relatively low speeds, so as to get high tractive forces whenstarting. Under the circumstances extraordinary high stresses are likelyto be created in the members of the transmission which may necessitatean increase in the dimensions of such members and thus make themextremely heavy; and because of the high tractive forces at the wheelsof the vehicle the friction limit may even be exceeded if the motorspeed is too high for favorable starting movement of thevehicle.

According to my invention these disadvantages are avoided by providingmeans preventing increase in the speed of the motor beyond a certainlimited range for a short period when starting, for example for vehiclespeeds up to three miles per hour. Consequently the value of thesecondary turning moment developed by the torque converter is adequatelylimited and practically held constant over the afore-mentioned periodand the stresses of the transmission elements remain within admissiblelimits.

For this purpose I prefer to provide a device which operates independence on the speed of the vehicle, that is in dependence on therevolutions of the out-going shaft of the hydraulic torque converter orof the shaft driving the wheels of the car.

All this will be understood best when having reference to the drawingwhich represents an example embodying my invention.

Fig. 1 is a diagrammatical side view, partly in section, of the drivingmachinery of a railroad motor car, some parts being shown on an enlargedscale.

Fig. 2 is a like view of a modified construction different from Fig. l.

The internal combustion engine I is provided with any normal fuelcarburetor or equivalent fuel feeding device 2 adapted to be operated byneans of a suitable actuating pedal or the like through fuel controllever 3, rod 4 and lost mo- 4 tion device 4|, which may be made to workautomatically in any well known manner (not illustrated). .On theoutgoing motor shaft 42 -fly wheel 5 is situated. There may as well beinserted a friction clutch 43, instead or in addition, 'as representedin Fig. 2. Shaft 42 then leads to a hydraulic torque converter 6 whichon its out-going right hand side drives shaft i4.-

To this shaft I4 driving shaft 8 is flexibly connected by means of auniversal joint 1. Shaft 8 at its right hand end is provided withbevelled gears for driving the axle ill with vehicle traction wheel Hthereon.

There is a pinion l2 rigidly connected to shaft l4 and in mesh withpinion l3 which has a driving connection with a centrifugal governor 15adapted to act on piston I 6 inside of cylinder 28 of a fluid controlvalve device against the pressure of compression spring l9. Piston l6has a cross channel I1 and a longitudinal channel [8, this latterchannel I8 connecting cross channel ll to the space to the right ofpiston l6. An

oil pump 40 driven by the engine I tends to supply oil under pressurethrough tube 2| which at 24 opens into control valve cylinder 28.Another opening 25 is situated close to opening 24, but the distancebetween these openings is so chosen that cross channel I! in piston l6may be either in connection with one or the other of these openings 24and 25. From opening 25 the oil may escape outward by means of tube 22,as indicated by the arrow.

There is a third opening 26 in controlvalve cylinder 20 situatedopposite to the upper end of cross channel I1, and connected to thisopening is tube 23 leading to fluid motor cylinder 2'! in which piston28 is adapted to move under the oil pressure from the space 33 above thepiston which connects with tube 23 against compression spring 29. Aflangestop 30 or the like prevents piston 28 from being moved to the topof the cylinder 21. In the idling position, when there is no oi1pressure inside of space 33, piston 28 is returned to its upper endposition under the pressure of spring 29 and bears against this stop 38.

A rod 3| is in rigid connection with piston 28, and at its upper end itis-provided with knob 32 or the like constitutingan adjustable fuelcontrolling limit stop against which the right hand end of lever 3 maybear when this lever is operated by means of rod 4 after it hastravelled over a certain way. v

The different parts of the. device are in the positions represented inFig. 1 when the engine I is not running. When the engine is started thefuel admission cannot be increased above a certain limit because fuelcontrol lever-3 after moving a limited distance is stopped by engagementof its right hand end against knob 32. Thus the engine is prevented fromdeveloping its entire output when the car is started, but laterv on,when the number of revolutions of the driven shaft it increases as thecar begins to move, the fuel control limit stop 32 is automaticallyadjusted downwardly and the carburetor is allowed to be opened to agreater extent to increase the fuel admission and the motor speed, independence on the speed of rotation of the driven shaft. As the speed ofrotation of shaft it increases, pinions l2 and I3 cause centrifugal.governor ii to move piston l6 to the right, so that pressure oil fromtube 2| may enter the valve device through cross channel l1 andlongitudinal channel i8 into the space to the right of pi on l6. Butthis increase inoil pressure causes piston It to be moved back again toits middle position shown in Fig. 1 to cut off tube 2| and open tube 23.Consequently, a certain increased oil pressure is established in channelI1 and transmitted through tube 23 to space 33 of cylinder 21 of thefuel control motor. creased pressure causes piston 28 to move downwardso that knob 32 also moves downward a1- lowing for further movement offuel control lever in the speed of shaft It at the output end of thetorque converter 8 and the resultant increases in the vehicle speed, thefuel limit stop is adjusted downwardly with a step-by-step motion sothat at last full opening of the carburetor is allowed.

Whilethe car is at rest and during slow starting movement thereof up toa predetermined speed limit, for instance 3 miles per hour, the turningmoment transmitted to the vehicle wheels This inis practically heldconstant, whereas it is allowed to decrease in the normal manner, inaccordance going specification it is not deemed necessary to givespecial illustrations thereof.

It is well known toprovide vehicle speed responsive controls operatingthrough the motor fuel feeding device when the vehicle attains a certainmaximum speed to prevent further increases in the speed of the motor andthe vehicle. Such prior device are readily distinguishable from thepresent invention broadly in that they do not control the motor speedwhen the vehicle is at rest and starting into motion. Further the priorcontrol devices do not purport to control the rate of increase in themotor speed, the motor accelerating rate, but only come into operationafter. the motor is revolving at a speed at which the drive through thetransmission produces the maximum vehicle speed desired.

I do not want to be limited to the details described or shown in thedrawing as many variations may occur to those skilled in the artwithout, deviating from the scope of my invention.

What I claim is:

1. In a motor car in combination an internal combustion engine, a speedand force transmission including a hydraulic torque converter, and

means for limiting the speed of said engine during ment of saidoperating lever and a fluid pressure device for adjusting the positionof said stop in accordance with opening and closing of the fluidpressure controlled by said fluid pressure valve.

2. In a vehicle having an internal combustion engine, transmissionmechanism for driving the vehicle from said engine, fuel feeding meansfor controlling the speed of the engine including an 0 operating lever,and means for automatically limiting the speed of the engine duringstarting movements of the vehicle comprising a governor fluid pumpdriven by said engine, and fluid conduits on opposite sides of saidvalve for connecting said pump with said cylinder to convey fluid underpressure into said cylinder when. said valve is open to thereby adjustthe position of the piston to permit increased extent of movement ofsaid operating lever.

KARL MAYBACH.

